If it’s a jar with liquid in it, juice for example, or pickles, beets, things like that, then SPANK the jar firmly on the bottom! Use the heel of your hand and do it three or four times. You may hear of the top release as you do it. Then it just takes a good grip.
Another tip is to put a wide rubber band around the lid. This gives you a very secure a grip to twist, it magically makes your hand stronger!
Then there’s the tried and true hot water cure. Run the lid under hot water for half a minute or so. The metal expands quicker than the glass does, which allows you to open the top more easily.
These are the best methods I know. They all work. Good luck!